App crashes after creating account with BYN currency

#### Steps to reproduce the behaviour
1. Create an account with BYN currency.
2. Hit Save. 

#### Expected behaviour
3. Account created and account list shown

#### Actual behaviour
3. App crashes
4. Any further attempts to start the app cause crashes

#### Software specifications
* GnuCash Android version: 2.1.4
* System Android version: 6.0.1
* Device type: All
